The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the referenced prior art forms part of the common general knowledge in Australia.
The disposal of drill cuttings from rigs and platforms at sea has come under increasing regulation on environmental grounds. The challenge is to accumulate cuttings on board and tranship to shore for ultimate disposal. Typically drill cuttings are accumulated in generic crane-hoistable skips which are loaded on to boat or barge for transport ashore. The number of skips required is large due to lifting limitations. Cranes are weather-dependent in operation, meaning drilling must cease when cuttings capacity on board is reached. The large number of skips necessary is an encumbrance on deck space and skips may not be safe to stack.
One solution proposed has been to use bulk pneumatic silos to handle drill cuttings as is done with other bulk materials such as barite or cement. However, traditional silos are not usually suitable, as the unique and highly variable physical properties of drill cuttings in many cases limits the ability to adequately discharge these tanks.
Traditionally the challenge of discharging high moisture and viscous materials from bulk silos was solved by having high angle conical bottoms in pressure silos. While this approach has been proven to work in most cases, this approach creates limitations in the storage capacity of the tank in a set footprint. One solution proposed by Halliburton is to have a straight sided tank with a “honey comb base” (HCB™) comprising an array of high-angle polygonal pyramids or cones dividing flow into an array of invert-conical or polygonal-pryramid outlets. The HCB tank does not rely on a high angle conical bottom to ensure mass flow discharge and can hold approximately 20% more bulk material in the same footprint as a high angle conical bottomed silo. The disadvantage is that such large tanks cannot be subjected to pressure-and-vacuum cycles necessary for efficient charge and discharge.